1. Field of the Invention
The present invention is directed generally to rotary valves having a wear-resistant seal between the valve stem and the body of the valve. More particularly, this invention is directed to valves for applications in which leakage-free operation is required over the life of the valve, such as nuclear power plants.
2. Description of Related Art
The use of flexible bellows, particularly thin-walled metal bellows to provide a seal between a valve body and valve actuator, such as the bellows disclosed in U.S. Pat. Nos. 2,659,569 and 3,782,685 is well-known in the art. However, since one end of the bellows is fixedly sealed to the valve body and the other end must move relative to the valve body during rotation, rotation causes the bellows to squirm. Friction and fatique induced by that squirming substantially reduce the useful life of the bellows.